Heat exchangers of a cross fin coil type have hitherto been widely used which has a multiplicity of heat transfer tubes arranged in parallel and a multiplicity of lamellar fins arranged orthogonally to the heat transfer tubes. In order to improve the heat transfer performance of heat exchangers of this type, it has been conventional to work the fins in various ways (as, for example, by providing notched and bent pieces of various configurations on the surfaces of the fins). However, such fin working have a limitation on the effectiveness for the improvement of the heat transfer performance.
Therefore, attempts have recently been made to develop heat exchangers having a new constructional arrangement which are known as mesh fin type heat exchangers (see, for example, Japanese Utility Model Application Laid-Open No. 61-192185).
A heat exchanger of the mesh fin type, as illustrated in FIGS. 10 and 11, comprises a multiplicity of heat transfer tubes 1, 1 . . . arranged in parallel, a multiplicity of mesh-form fins 2, 2 . . . arranged parallel to the axes of the heat transfer tubes 1, 1 . . . and joined to the outer peripheries of the heat transfer tubes 1, and tube plates 3 supporting the heat transfer tubes 1, 1 . . . at the ends thereof. The heat transfer tubes 1 and the mesh-form fins 2 are joined together usually by soldering or brazing after the mesh-form fins 2, 2 . . . are tightly held against the heat transfer tubes 1 from opposite sides thereof.
For the purpose of holding the mesh-form fins 2, 2 . . . against the heat transfer tubes 1, 1 . . . from opposite sides thereof as aforesaid, however, one problem is that the mesh-form fins 2, 2 be preformed at predetermined locations with grooves conforming to the outer peripheral surface of the heat transfer tubes 1. Another problem is that the process of placing mesh-form fins 2, 2 in superposed relation and fixing them together requires a high level of technical skill.